Currently, the liquid crystal display technology has been widely used in display of televisions, cell phones and public information, and its picture quality is an important condition for the success of these products. And among a large number of parameters for deciding the picture quality, the brightness of liquid crystal display is an important parameter standard.
In the prior art, the biggest feature of an array substrate of a display device of a liquid crystal display mode of IPS (In Plane Switching) is that, a pixel electrode and a common electrode of it are on the same plane, that is, the common electrode and the pixel electrode are disposed in the same layer. The structure of an array substrate of an existing IPS mode liquid crystal display device, as illustrated in FIG. 1, mainly includes a gate line 1, a data line 2, a thin film transistor 3, a pixel-electrode connecting section 4, a pixel electrode 5, a common electrode 6, a common-electrode connecting section 7 and a common electrode line 8. The region defined by adjacent gate lines and adjacent data lines is a pixel region; a pixel electrode and a common electrode are disposed within a pixel region in a manner of lying in the same layer and being alternate; for the thin film transistor 3, its gate electrode of is connected to the gate line 1, its source electrode is connected to the data line 2, and its drain electrode 9 is connected to the pixel-electrode connecting section 4; and the common electrode line 8 is connected to the common-electrode connecting section 7 through via holes. For the sake of ensuring that the voltage on a pixel electrode within the time of one frame picture is relatively constant, and because the pixel electrode 5 and the common-electrode connecting section 7 are disposed in the same layer, a storage capacitor cannot be arranged between them, and a separate zone is required for arrangement of the storage capacitor. For example, a storage capacitance electrode 91 is disposed at one end near the thin film transistor 3, and one branch 81 of the common electrode line 8 is introduced to the vicinity of the thin film transistor 3, so that a storage capacitor is formed by the common electrode line 8 and the storage capacitance electrode 91. Such a structure brings about the fact that a pixel region is occupied too much by areas occupied by the common electrode line 8 and the thin film transistor 3, and thus, the aperture ratio is decreased, and the light transmittance is reduced. Consequently, the display brightness of the liquid crystal display device is affected.
Therefore, how to raise the aperture ratio of an IPS mode liquid crystal display device is an urgent problem to be solved by those skilled in the art.